This invention relates to power distribution transformers, and more particularly to power distribution transformers incorporating primary circuit breaker devices such as the ones disclosed in U.S. Pat. No. 4,611,189, issued Sept. 9, 1986, and U.S. Pat. No. 4,435,690, issued Mar. 6, 1984. These breaker devices provide primary and secondary current interruption for both extended overloads and fault currents in a transformer, and both include a temperature sensing system responsive to fault current in the primary winding and to increases in temperature of insulating fluid in the transformer, due to overloads or incipient faults. The specifications of U.S. Pat. Nos. 4,611,189 and 4,435,690 are incorporated herein by reference.
A potential problem associated with power distribution transformers incorporating primary circuit breaker devices arises when a re-closing of a transformer having a primary fault is attempted. Although the transformer primary circuit breaker device is designed to operate properly if this is attempted, additional arcing of the faulted area could produce an unsafe condition for the lineman attempting the re-closing.
Attention is directed to the following U.S. Patent references:
______________________________________ Inventor Patent No. Issued ______________________________________ Jones 1,740,307 December 17, 1929 Hoffer 1,887,489 November 15, 1932 Zmuda et al. 3,166,894 January 26, 1965 Johnsen et al. 3,544,942 December 1, 1970 Korner et al. 3,985,988 October 12, 1976 Kasamatsu 4,380,001 April 12, 1983 Link et al. 4,435,690 March 6, 1984 Mikulecky 4,550,298 October 29, 1985 Mikulecky 4,611,189 September 9, 1986 ______________________________________